It is well known to use a flapper type subsurface well safety valve, as shown in U.S. Pat. No. 4,161,219, in which the flapper seats on a metal seat and an elastomer seal for controlling the flow of well fluids from producing oil and/or gas wells. However, the safety valve must be able to withstand hostile environments in which high temperatures and pressures are encountered and the well fluids frequently contain corrosive fluids and abrasive particles such as sand. Since the safety valves may be required to remain in service for many years and still be able to close and shut off high pressures, it is important that the flapper valve and its coacting seat be able to maintain their integrity. However, it is well known that elastomer seals frequently fail under such conditions. Flexible metal seals, such as shown in U.S. Pat. No. 4,513,946, which have been proposed in other valves, would not be satisfactory for use in a subsurface well safety valve.
The present invention is directed to an improved seat in a flapper type well safety valve having a solid metal annular seat capable of withstanding extremely high pressures and supporting a flexible second annular metal seal which initially makes contact with the flapper before the flapper contacts the solid seat on closing for providing a redundant long lasting seal which can withstand the harsh environmental conditions in a high temperature, high pressure oil and/or gas producing well.